Backyard Aquaponics
A place to discuss aquaponics

i am in south eastern wisconsin.

i am absolutly inlove with aquaponics now. but i found out about it torwards the end of summer

so my question...

if i go to the store pick up some pvc pipe and some clear plastic rolls.

build a greenhouse in the backyard. and set up a solar water heater to recirculate water in a 55 gallon barrel in the center of the greenhouse.

can i keep it warm enough do you guys think to keep an ap system going through winter.

the solar heater im thinking of utilizes a coil from the back of a fridge encased in a black box with a glass window on the top of it. with tubing going down to the 55 gallon barrel

i've heard of people making the same system only using a 5 gallon bucket and by recirculating the water over the course of an hour they had 177 degree F water in there 5 gallon bucket.

money is extreamly tight atm. i priced the greenhouse parts at 15 dollars total cost

Have you read any of Nick Pine's postings about solar closets and passive solar gain? He explains the math and mechanics of heat transfer.

I'd say $15 isn't a lot to risk -- though I've spent that much on hinges and a latch for the door of my greenhouse.

i have everything i think i'd need exept for the pvc and the plastic.

In Iowa, so I think I get about the same winters as you do. I would not bother with a pvc and plastic green house for winter growth. You will not be able to keep it warm enough to grow anything without providing heat through the night.

thats what i was hoping to do with the solar water heater is to build thermal mass.

i have seen fan's that sit ontop of stoves that run on thermal heat.

they have one's that start at fairly low heats. i could even use one of them ontop of the 55 gallon barrel to circulate the air inside to keep it all heated.

You may want to try double layering your greenhouse in plastic if you go that route. One layer on the outside of the struts and one on the inside, creating an insulating air gap. The only experience I have with your winters is what my sister told me when she went to Madison. From what I gather, getting to -10F is not uncommon. So you'll need big thermal masses to absorb heat during the day and release over night. You can read Nick Pine's stuff as ems suggested, it's online somewhere.

But a large body of water (say, a big fish tank) should be a big step in the right direction for thermal stabilization. Just make sure it is insulated from the ground but NOT insulated from the air. Might be tricky depending on exactly how the dynamics go.

If you can build your greenhouse up against a south facing wall, that is your best bet. Build it up against the wall on the house or other insulated building. The south wall (would be the north facing wall of the greenhouse) would prevent heat loss and is not needed for the sun anyways. That way, being an insulated wall(that has heat on the other side) you are losing a lot less heat and saving on some greenhouse construction costs. The east and west walls should be double lined with plastic at the very minimum. If you can afford to build walls outright then the better.

If you can, go for as much heat mass that you can that is not actually the fish tank. The less temperature fluctuation the fish get from night to day the better (at least not extremes). utilize all the non used space with thermal mass. Good ideas sometimes heard are jugs, cans etc. Preferably paint them black or a dark colour.

Google "solar greenhouse" and you will get many ideas. I'm looking at building something up here in Canada that requires no heat at all for most of the winter and can still grow. My problem is finding a fish that can handle significant temperature fluctuations.

To give you an idea of what you would need for thermal mass.
One BTU is the amount of heat required to change the temperature of one pound of water one degree Fahrenheit. (Talking sensible heat, and pure water).
So a 55 gallon barrel would have roughly a 440 BTU capacity, given water weighs roughly 8lbs a gallon. 55 x 8 = 440.
For example lets say we can get the water in the barrel up to 100 degrees during the day, and at night down to 50 degrees.
In this example the barrel would hold a total of 22,000 BTU.
Now just talking the heat energy (BTU's) of 22,000, How big of a space would this heat?

no clue you didnt finnish telling us

Found this: http://reviews.ebay.com/How-many-Btu-s- ... LISTINGS:5

Looks like you are in the 55 BTU/sq ft region. That probably assumes better insulation than your greenhouse will have.

So your equation would be sq ft*55 (or 70 or 100)/8 = gallons of water needed for thermal mass.

At least, I think that's right .

Too many variables for me to figure it out. How many degrees do you need to heat? What are the losses of the structure?
I don't think you can get enough heat in Wis. through the winter with a 55 gallon barrel of water, to keep an ap system going even if you get the water up to 177 degrees.
So unless your willing to beef up the structure and add alot more thermal mass then one barrel will provide its a no go IMHO.
Even then it may be a useless effort given you will only be providing heat thru solar radiation. One blizard day and your plants are frozen.
Hope I was helpfull in answering your question.
Been there done that.
So perhaps your next question should be, (How do I satisify the AP addiction thru the Cold Winter Months?)

Aren't all greenhouses heated by solar radiation?

Also, in addition to having a large thermal mass you can create heat sources in all kinds of ways. My favorite is composting. Temperatures of a thermophillic compost pile will get up past 130F.

Again, to help maintain night time temps up, I would recommend covering the tanks, and bypassing the growbeds and circulating the water through an insulated biofilter to keep the aeration going and help keep the waste levels from getting high at night.

Depending on the temps you need to maintain, that's what will help figure out whether or not it's feasible.

Just my 2 cents worth.

If its a matter of just keeping fish alive then I'd agree bypass the growbeds but if you want ap veggies to survive the cold nights I think it would be better to keep cycling the water.